Roll position setting method of Sendzimir mill

ABSTRACT

A roll position setting method for a Sendzimir mill that can easily adapt to combinations of roll sets and enables each roll to be set in a position optimal for operation. Each eccentric angle of first and second backing bearings is set by adjusting a bottom screw device so that an upper surface of the bottom work roll reaches a pass line of the rolled material based on first function. For top side roll setting, the eccentric angle of fourth backing bearings is set by adjusting top side screw devices so that a second function, different from the first function, is optimized.

TECHNICAL FIELD

The present invention relates to a roll position setting method forappropriately setting the roll positions of a Sendzimir mill by use of aplurality of screw down devices.

BACKGROUND ART

When high-hardness materials to be rolled, such as stainless steel, arecold rolled, small diameter work rolls are adopted in a rolling mill.There is a Sendzimir mill as a representative of such rolling mills.

FIG. 1 is a block diagram showing a general Sendzimir mill with 20rolls. The Sendzimir mill shown in FIG. 1 has a roll arrangement made upof work rolls 2 and 3 in a top and bottom pair, first intermediate rolls4 to 7 in quantities of two each on top and bottom, second intermediaterolls 8 to 13 in quantities of three each on top and bottom, and backingbearings 14 to 21 in quantities of four each on top and bottom.

Each of the backing bearings 14 to 21 is provided with an eccentricitymechanism, and the position of each of the rolls 2 to 13 is determinedby the setting of each eccentric angle of the backing bearings 14 to 21.Each eccentric angle of the backing bearings 14 to 21 is adjusted by aplurality of screw down devices arranged above and below. Concretely,the screw down devices are composed of a top screw down device 22, abottom screw down device 23, top side screw down devices 24 and 25, andbottom side screw down devices 26 and 27.

On a Sendzimir mill having the above-described arrangement, before thestart of rolling, the setting of each of the screw down devices 22 to 27has hitherto been carried out in the method described below.

That is, each eccentric angle of the backing bearings 18 to 21 isdetermined so that the bottom work roll 3 maintains pass line, and setby the bottom screw down device 23 and the bottom side screw downdevices 26 and 27.

On the other hand, the top screw down device 22 is used to obtaindesired thickness. That is, the eccentric angle of the backing bearings15 and 16 is adjusted by the top screw down device 22 by constant loadcontrol so that the rolling load (or pressure) obtains a preset value.Incidentally, after the start of rolling, the eccentric angle of thebacking bearings 15 and 16 is appropriately adjusted by gauge controlwhich involves adjusting the gap between the work rolls on the basis ofmeasured thickness values measured by thickness meters.

That is, the top screw down device 22 is not operated on the basis ofthe preset value of the eccentric angle of the backing bearings 15 and16, which is not calculated actually. Therefore, it is impossible toknow the eccentric angle of the backing bearings 15 and 16 before ascrew-down is performed actually. Incidentally, the eccentric angle ofthe backing bearings 15 and 16 varies also depending on the setting ofthe eccentric angle of the backing bearings 14 and 17 which is adjustedby the top side screw down devices 24 and 25.

And in a conventional method, the same value was used as the presetvalues of the four side screw down devices 24 to 27 in consideration ofsymmetricity. For this reason, the eccentric angle of the backingbearings 14 and 17 was set at the same value as the eccentric angle ofthe backing bearings 18 and 21 adjusted by the bottom side screw downdevices 26 and 27. Due to such circumstances operation has sometimesbeen carried out with the eccentric angle of the backing bearings 15 and16 undesirable setting.

Also, as a conventional art, there has been proposed a roll positionsetting method which involves setting the position of each roll of aSendzimir mill also in consideration of the eccentric angle of backingbearings by a top screw down device (refer to Patent Document 1, forexample).

Concretely, in the roll position setting method described in PatentDocument 1, first, the eccentric angle by the top screw down device isdetermined so that the relation between the cylinder position of the topscrew down device and the work roll position be linear. Next, theeccentric angle by the top and bottom side screw down devices aredetermined to satisfy roll gap, which is given by another calculation,based on the geometric relation of the top side roll set. Lastly, theeccentric angle by the bottom screw down device is determined from asimplified expression on the basis of that by these side screw downdevices. And the above-described calculations are repeated until asolution which meets these conditions is obtained.

-   Patent Document 1: Japanese Patent Laid-Open No. 10-263638

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

In the roll position setting method described in Patent Document 1,problems as described below remain still unsolved.

1. Although the eccentric angle of the backing bearings adjusted by thetop screw down device is set in consideration of gauge control, from thestandpoint of operation such a setting method is not always optimal.

2. The eccentric angles of the backing bearings adjusted by the top andbottom side screw down devices are all set at the same value and,therefore, combinations of roll sets are remarkably limited.

3. Because of the use of a simplified expression in pass linedetermination, it is impossible to avoid the error.

The present invention has been made to solve problems as described aboveand the object of the invention is to provide a roll position settingmethod of a Sendzimir mill which can easily adapt to combinations ofroll sets and enables each roll to be set in a position optimal foroperation.

Means for Solving the Problems

A roll position setting method of a Sendzimir mill of the presentinvention is a roll position setting method of a Sendzimir mill thatcomprises top and bottom work rolls which roll a rolled material, aplurality of backing bearings having an eccentricity mechanism, a bottomscrew down device which adjusts the eccentric angle of first backingbearings arranged in a middle part, which belong to the backing bearingspressing the bottom work roll from below, bottom side screw down deviceswhich adjust the eccentric angle of second backing bearings, whichbelong to the backing bearings pressing the bottom work roll from below,arranged on the entry side and delivery side of the first backingbearings, a top screw down device which adjusts the eccentric angle ofthird backing bearings arranged in a middle part, which belong to thebacking bearings pressing the top work roll from above, and top sidescrew down devices which adjust the eccentric angle of fourth backingbearings arranged on the entry side and delivery side of the thirdbacking bearings, which belong to the backing bearings pressing the topwork roll from above, which comprises a bottom side setting step ofsetting each eccentric angle of the first and second backing bearings byadjusting the bottom screw down device and the bottom side screw downdevices so that an upper surface of the bottom work roll reaches passline of the rolled material on the basis of a prescribed first function,and an top side setting step of setting the eccentric angle of thefourth backing bearings by adjusting the top side screw down devices sothat a second function different from the first function is optimized.

Effect of the Invention

According to the present invention, it is possible to easily adapt tocombinations of roll sets and to set each roll in a position optimal foroperation.

BRIEF OF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a general Sendzimir mill.

FIG. 2 is a diagram showing a line arrangement including the Sendzimirmill.

FIG. 3 is a diagram to explain a roll position setting method of thebottom side roll set.

FIG. 4 is a diagram to explain an example of a roll position settingmethod of the top side roll set.

FIG. 5 is a flowchart showing an example of a roll position settingmethod of the top side roll set.

DESCRIPTION OF SYMBOLS

-   -   1 rolled material,    -   2 top work roll,    -   3 bottom work roll,    -   4-7 first intermediate roll,    -   8-13 second intermediate roll,    -   14-21 backing bearing,    -   22 top screw down device,    -   23 bottom screw down device,    -   24-25 top side screw down device,    -   26-27 bottom side screw down device,    -   28-29 tension reel,    -   30-31 thickness meter,    -   32-33 sensor roll

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in more detail with reference tothe accompanying drawings. Incidentally, in each of the drawings, likenumerals refer to like or similar parts and overlaps of description ofthese parts are appropriately simplified or omitted.

First Embodiment

The basic arrangement of the Sendzimir mill in a first embodiment is thesame as shown in FIG. 1. As described above, this Sendzimir mill issuitable for rolling a hard material 1, such as stainless steel in coldmill. A concrete arrangement of this Sendzimir mill will be describedbelow.

Reference numerals 2 and 3 denote work rolls in a top and bottom pair,and reference numerals 4 to 7 denote first intermediate rolls, whichpress the work rolls 2 and 3 toward the rolled material 1, in quantitiesof two each on top and bottom. The top work roll 2 is pressed downwardby the top side first intermediate rolls 4 and 5, and the bottom workroll 3 is pressed upward by the bottom side first intermediate rolls 6and 7. Reference numerals 8 to 13 denote second intermediate rolls,which press the first intermediate rolls 4 to 7 toward the rolledmaterial 1, in quantities of three each on top and bottom (referencenumerals 8, 10, 11 and 13 denote drive rolls and reference numerals 9and 12 denote idle rolls).

Reference numerals 14 to 21 denote backing bearings, which press thesecond intermediate rolls 8 to 13 to the rolled material 1, inquantities of four each on top and bottom. The backing bearings 14 to 17arranged above the rolled material 1 press the top work roll 2 fromabove via the second intermediate rolls 8 to 10 and the firstintermediate rolls 4 and 5. The backing bearings 18 to 21 arranged belowthe rolled material 1 press the bottom work roll 3 from below via thesecond intermediate rolls 11 to 13 and the first intermediate rolls 6and 7. The Sendzimir mill in a first embodiment has a 20-rollarrangement like this.

Each of the backing bearings 14 to 21 is provided with an eccentricitymechanism. And the position of each of the rolls 2 to 13 except thebacking bearings 14 to 21 is determined by the setting of the eccentricangle of the backing bearings 14 to 21. The eccentric angle of thebacking bearings 14 to 21 is adjusted by a plurality of screw downdevices arranged above and below the rolled material 1. Concretely, thescrew down devices are broadly divided into four kinds: a top screw downdevice 22, a bottom screw down device 23, top side screw down devices 24and 25, and bottom side screw down devices 26 and 27. Incidentally, theillustration of the concrete arrangement of each of the screw downdevices 22 to 27 is omitted.

The top screw down device 22 is arranged substantially just above thetop work roll 2, and has the function of adjusting the eccentric angleof the backing bearings 15 and 16 (third backing bearings) arranged in amiddle part, which belong to the backing bearings 14 to 17. The bottomscrew down device 23 is arranged substantially just under the bottomwork roll 3, and has the function of adjusting the eccentric angle ofbacking bearings 19 and 20 (first backing bearings) arranged in a middlepart, which belong to the backing bearings 18 to 21.

The top side screw down devices 24 and 25 are each arranged on bothsides (the entry side and delivery side or called also the right sideand left side) of the top screw down device 22, and have the function ofadjusting the eccentric angle of the backing bearings 14 and 17 (fourthbacking bearings) arranged on the entry side and delivery side of thebacking bearings 15 and 16. Concretely, the eccentric angle of thebacking bearing 14 is adjusted by the top side screw down device 24 andthe eccentric angle of the backing bearing 17 is adjusted by the topside screw down device 25.

The bottom side screw down devices 26 and 27 are each arranged on bothsides (the entry side and delivery side) of the bottom screw down device23, and have the function of adjusting the eccentric angle of thebacking bearings 18 and 21 (second backing bearings) arranged on theentry side and delivery side of the backing bearings 19 and 20.Concretely, the eccentric angle of the backing bearing 18 is adjusted bythe bottom side screw down device 26 and the eccentric angle of thebacking bearing 21 is adjusted by the bottom side screw down device 27.Incidentally, each of the screw down devices 22 to 27 is configured tobe able to adjust (set) the eccentric angle of the respective backingbearings each independently.

Next, a description will be given of a line arrangement having theSendzimir mill of the above-described arrangement.

FIG. 2 is a diagram showing a line arrangement including the Sendzimirmill. When a difficult-to-be-rolled material 1 such as stainless steelis rolled by being moved from the left side to the right side in FIG. 2,the rolled material (coil) 1 is unwound by left tension reel 28 and therolled material 1 is delivered to the Sendzimir mill. And after rollingthe rolled material 1 on the Sendzimir mill, the rolled material 1 iswound by right tension reel 29. In case of stainless steel rolling, theabove-described rolling operation is reciprocally performed and therolled material 1 is made thin to desired thickness in some passes.

When stainless steel is rolled, in general, rolling is reciprocallyrepeated, with part of the rolled material 1 kept constantly wound onboth tension reels 28 and 29. Furthermore, though not shown in FIG. 2,usually, on the outside of the tension reel 28 or 29 there is provided apay off reel which pays off the rolled material 1.

Incidentally, reference numerals 30 and 31 in FIG. 2 denote thicknessmeters installed on the entry side and delivery side of the Sendzimirmill. After the start of rolling, various kinds of gauge controlfunctions work on the basis of measurement results of the thicknessmeters 30 and 31 so that desired thickness is obtained. Also, shapecontrol is performed on the basis of measurement results of a sensorroll installed on the delivery side (a sensor roll 33 in the case of therolling direction shown in FIG. 2, a sensor roll 32 in the case of aleftward rolling direction).

In the Sendzimir mill having the above-described arrangement, as amatter of course, before the start of rolling it is necessary to setroll positions by determining the eccentric angle of each of the backingbearings 14 to 21 by use of each of the screw down devices 22 to 27. Aconcrete setting method of roll positions will be described below.

For a roll set arranged below the rolled material 1 (hereinafterreferred to as “the bottom side roll set”), it is important to keep thepass line. That is, each eccentric angle of the backing bearings 18 to21 is adjusted by the bottom screw down device 23 and the bottom sidescrew down devices 26 and 27, whereby setting is performed on the basisof a prescribed function (a first function) so that an upper surface ofthe bottom work roll 3 reaches the pass line.

FIG. 3 is a diagram to explain a roll position setting method of thebottom side roll set. A description will be given of a concrete rollposition setting method related to the bottom side roll set on the basisof FIG. 3. In FIG. 3, α^(BOT) denotes the eccentric angle of the backingbearing 18 capable of being adjusted by the bottom side screw downdevice 26, β^(BOT) denotes the eccentric angle of the backing bearing 19capable of being adjusted by the bottom screw down device 23, and Ddenotes roll diameter (the suffix of D indicates roll number. Forexample, D₃ indicates the diameter of the work roll 3, and D₁₉ indicatesthe diameter of the backing bearing 19). Incidentally, FIG. 3 shows onlydetails of the left side half because the bottom side roll set islaterally symmetrical.

Keeping the pass line for the bottom side roll set means that in FIG. 3,a gap formed between the pass line and the upper surface of the bottomwork roll 3 is set at 0. As shown in FIG. 3, because the diameter ofeach roll and the relation of the rolls in contact are known, it ispossible to geometrically calculate this gap itself from each eccentricangle of the backing bearings 18 to 21 (i.e., each set value of thebottom screw down device 23 and the bottom side screw down devices 26and 27).

However, it is very difficult to find the eccentric angle of the backingbearings 18 to 21 by the back calculation of the above-describedcalculation formula at the gap calculation. Therefore, in actualrolling, before the start of rolling, each eccentric angle of thebacking bearings 18 to 21 is found by the following method and thebottom screw down device 23 and the bottom side screw down devices 26and 27 are appropriately set.

That is, before the start of rolling, first, each eccentric angle of thebacking bearings 18 to 21 is changed in the range in which setting bythe bottom screw down device 23 and the bottom side screw down devices26 and 27 is possible, and a gap generated at that time is calculated.And each eccentric angle of the backing bearings 18 to 21 is found outby the above-described calculation so that the gap becomes within aprescribed range, for example, as given by−0.1<Gap<0.1 [mm]  (1)

Incidentally, in general, the roll sets of a Sendzimir mill are arrangedlaterally symmetrical, and therefore the above-described calculation iscarried out by using the roll diameter shown below left in FIG. 3, forexample. By using the above-described method, before the start ofrolling, it is possible to appropriately set the bottom screw downdevice 23 and the bottom side screw down devices 26 and 27 so that theupper surface of the bottom work roll 3 reaches the pass line.

Next, a concrete description will be given of a roll position settingmethod of a roll set arranged above the rolled material 1 (hereinafterreferred to as “the top side roll set”).

For the backing bearings 15 and 16, the eccentric angle thereof is setby the adjustment of the top screw down device 22 so that the rollingload P to the rolled material 1 becomes a preset value. For the backingbearings 14 and 17, the eccentric angle thereof is set by the adjustmentof the top side screw down devices 24 and 25 so that a prescribed secondfunction different from the above-described first function becomesoptimum.

Incidentally, for the top side roll set, concretely the following twokinds of setting methods are conceivable.

Setting method A: The above-described second function is expressed bythe ratio of a force received by the top work roll 2 from the rolledmaterial 1 to a force applied to the top screw down device 22 (a forcegiven by the top screw down device 22 to the backing bearings 15 and16), and the eccentric angle of the backing bearings 14 and 17 is set sothat this second function becomes maximal.

Setting method B: The above-described second function is composed of acost function which has the eccentric angle of the backing bearings 15and 16 and the eccentric angle of the backing bearings 14 and 17 asvariables, and the eccentric angle of the backing bearings 14 and 17 isset so that this second function becomes minimal.

First, the above-described setting method A will be described on thebasis of FIG. 4.

FIG. 4 is a diagram to explain an example of a roll position settingmethod of the top side roll set. Incidentally, p in FIG. 4 denotes apressure applied to the top screw down device 22, and P denotes arolling load received by the rolled material 1 (an upward force receivedby the top work roll 2 from the rolled material 1). P₁ to P₈ denote thetransmission relations of forces to each roll.

Concretely, P₁ is a component force generated by dividing the rollingload P in the direction of a straight line connecting the center of theroll 2 and the center of the roll 4, P₂ is a component force generatedby dividing the component force P₁ in the direction of a straight lineconnecting the center of the roll 4 and the center of the roll 8, and P₃is a component force generated by dividing the component force P₁ in thedirection of a straight line connecting the center of the roll 4 and thecenter of the roll 9. Similarly, P₄ and P₅ are each a component forcegenerated by dividing the component force P₂, P₆ is a resultant force ofthe P₃ received from the roll 4 and of the component force P₃ receivedfrom the roll 5, P₇ is a component force generated by dividing theresultant force P₆ in the direction of a straight line connecting thecenter of the roll 9 and the center of the roll 15, and P₈ is aresultant force of the component force P₅ and the component force P₇.Incidentally, because the top side roll set is laterally symmetrical,the foregoing provides a detailed description of only the left sidehalf.

Ratio of above-described pressure p to rolling load PRatio=(Rolling load P)/(pressure p)  (2)can be geometrically calculated from each eccentric angle of the backingbearings 14 to 17 (i.e., each set value of the top screw down device 22and the top side screw down devices 24 and 25), because the diameter ofeach roll and the relation of the rolls in contact are known. Therefore,each eccentric angle of the backing bearings 14 to 17 is sequentiallychanged in a rage in which setting by top screw down device 22 and thetop side screw down devices 24 and 25 is possible, and a combination inwhich the ratio expressed by Expression (2) above becomes maximal can beselected in this change.

However, the top screw down device 22 sets the eccentric angle of thebacking bearings 15 and 16 so that the rolling load P (or the pressurep) becomes the preset value. For this reason, the eccentric angle of thebacking bearings 15 and 16 does not always coincide with the eccentricangle found so that the ratio expressed by Expression (2) above becomesmaximal. That is, this means that the ratio calculated by Expression (2)above does not always become maximal in a roll position in the casewhere roll gap closes until rolling load P reaches the preset value.

Hence, the eccentric angle of the backing bearings 15 and 16 in roll gapclose condition (a set value of the top screw down device 22) isestimated and if Expression (2) above is evaluated by using thisestimated eccentric angle, then it is possible to constantly make theratio maximal in roll gap close condition.

Hereinafter, with the aid of the flow of FIG. 5 a description will begiven of a method of finding the above-described ratio by estimating theeccentric angle of the backing bearings 15 and 16 in roll gap closecondition.

FIG. 5 is a flowchart showing an example of a roll position settingmethod of the top side roll set. After the roll position setting of thebottom side roll set as described above (S101), first, each eccentricangle of the backing bearings 14 to 17 is found so that the lowersurface of the top work roll 2 reaches the pass line (S102). Thiscalculation at S102 can be performed in the same manner as the casewhere each eccentric angle of the backing bearings 18 to 21 iscalculated at S101.

Incidentally, at S102 above, as described above, each eccentric angle ofthe backing bearings 14 to 17 may be found under the condition that thelower surface of the top work roll 2 is caused to reach the pass line,or each eccentric angle may also be found by using some other conditionby changing this condition.

The value obtained at S102 is a value obtained when the rolled material1 does not exist, and during actual rolling, the rolled material 1having prescribed thickness is present between the top and bottom workrolls 2 and 3. As described above, during actual rolling, each eccentricangle of the backing bearings 15 and 16 is set by the top screw downdevice 22 so that the rolling load P (or the pressure p) becomes apreset value. That is, the lower surface of the top work roll 2 in rollgap close condition is pushed back from the pass line by just thicknessof the rolled material 1 and furthermore moves downward to a position soas to cancel out the amount of mill stretch occurring due to the rollingload (or the pressure).

From the foregoing, the position of the lower surface of the top workroll 2 becomes a position where the lower surface opens (moves upward)by just the amount of gap change given by the following expression fromthe pass line (S103):ΔS=fs(h,P)  (3)where, h is the delivery thickness.

Incidentally, because the Sendzimir mill shown in FIGS. 1 to 4 has a20-roll arrangement, the hysteresis is very large and the calculation ofthe above-described amount of gap change ΔS may sometimes be difficult.In such a case, it becomes possible to obtain stable calculation resultsif a prescribed offset amount from the pass line is preset on the basisof empirical values and this offset amount is used instead of theabove-described amount of gap change. Also, if a table which isstratified by steel grades and the like is prepared beforehand, it ispossible to cope with various situations and it becomes possible toeasily perform maintenance.

Next, the eccentric angle of the backing bearings 15 and 16 in roll gapclose condition is found on the basis of the amount of gap change ΔSobtained at S103. At this time, with the eccentric angle of the backingbearings 14 and 17 (i.e., a set value of the top side screw down devices24 and 25) kept fixed, the gap is compensated for by the eccentric angleof the backing bearings 15 and 16 (i.e., the top screw down device 22).This calculation is basically the same as the calculation for pass linesetting. That is, each eccentric angle of the relevant backing bearings14 to 17 is found by using the following expression as a conditionalexpression in place of Expression (1) while changing only the eccentricangle of the backing bearings 15 and 16 (S104):ΔS−0.1<Gap<ΔS+0.1 [mm]  (4)

Lastly, the ratio of Expression (2) is calculated on the basis ofcombinations of each eccentric angle obtained by the calculation at S104(S105). Such calculations are carried out in a range in which thesetting of each eccentric angle of the backing bearings 14 to 17 ispossible, and a value at which the ratio becomes maximal is set as theeccentric angle of the backing bearings 14 and 17. The top side screwdown devices 24 and 25 are set like this, whereby the above-describedratio becomes maximal in roll gap close condition when the top screwdown device 22 is set on the basis of the rolling load (or thepressure).

By setting roll positions by the above-described method A, rolling isdone in the minimum energy and it is efficient. By setting the ratiogiven by Expression (2) at a maximum, it is possible to take a largedraft per pass and as a result of this, it also improves productionefficiency by reducing the number of passes. Furthermore, according tothe above-described method, because the top side screw down devices 24and 25 and the bottom side screw down devices 26 and 27 are differentlyset, this offers the advantages that setting limitations related tocombinations of roll sets become lax and that roll management becomeseasy.

Next, the above setting method B will be described.

As described above, in the setting method A, each eccentric angle wasset so that the ratio given by Expression (2) becomes maximal. Incontrast to this method, in the setting method B, the purpose is toperform setting so that the eccentric angle of the backing bearings 15and 16 set by the top screw down device 22 and the eccentric angle ofthe backing bearings 14 and 17 each become a desired value.

That is, in the setting method B, instead of making the ratio given byExpression (2) above maximal, the following cost function is considered:J=f _(j)(α^(TOP)−α^(TOP) ^(—) ^(AIM),β^(TOP)−β^(TOP) ^(—) ^(AIM))Eccentric angles (α^(TOP), β^(TOP)) which minimize this cost function Jare used as set values. In this expression, variables have the followingmeanings:

α^(TOP): Eccentric angle of the backing bearings 14 and 17 [deg]

α^(TOP) ^(—) ^(AIM): Target value of eccentric angle of the backingbearings 14 and 17 [deg]

β^(TOP): Eccentric angle of the backing bearings 15 and 16[deg]

β^(TOP) ^(—) ^(AIM): Target value of eccentric angle of the backingbearings 15 and 16 [deg]

Incidentally, also in this setting method B, it is possible to performevaluation by using eccentric angles in roll gap close condition as withthe setting method A.

Because the setting methods A and B differ from each other in the costfunctions alone and are the same in other calculation, the detailexplanation is omitted for the setting method B. As a result of this, itis possible to set the eccentric angle of the top side backing bearings14 to 17 at a desired value.

For the reason that damage in case of strip breakage can be reduced byproviding gap in the opening direction of screw-down and that too muchclosing is not preferable as the initial position in the point of viewof rolling the rolled material in multiple passes continuously, it isoften desired that the eccentric angle of the backing bearings 15 and 16be set around the center position in the allowable range. The settingmethod B is intended for use in such a case and contributes to stableoperation.

In the calculation of the eccentric angle of the top side backingbearings, because in general the arrangement is laterally symmetrical aswith the bottom side backing bearings, the calculation is performed byusing the top left roll diameter, for example.

Incidentally, for the setting of each eccentric angle of the backingbearings, it is apparent that the same effect can be achieved as thepresent invention even when the top side backing bearings and the bottomside backing bearings are applied to a relation reverse to theabove-described relation. Furthermore, in actual rolling, an offset maysometimes be considered to the pass line setting due to operationalreasons. The present invention can be easily applied also to such acase.

INDUSTRIAL APPLICABILITY

Although in the above-described embodiment the description shows theapplication to Sendzimir mill, the present invention is not limited bythis, and it is possible to apply the present invention to rolling millshaving similar functions, for example, cluster mill.

1. A roll position setting method for setting rolls of a Sendzimir millthat includes top and bottom work rolls which roll a rolled material, aplurality of backing bearings having an eccentricity mechanism, a bottomscrew device which adjusts eccentric angle of first backing bearings, ofthe backing bearings, arranged in a middle part, and which press thebottom work roll from below, bottom side screw devices which adjusteccentric angle of second backing bearings, of the backing bearings, andwhich press the bottom work roll from below, located on an entry sideand a delivery side of the first backing bearings, a top screw devicewhich adjusts eccentric angle of third backing bearings, of the backingbearings, located in a middle part, and which press the top work rollfrom above, and top side screw devices which adjust eccentric angle offourth backing bearings, of the backing bearings, located on an entryside and a delivery side of the third backing bearings, which press thetop work roll from above, the method comprising: setting the eccentricangles of the first and second backing bearings by adjusting the bottomscrew device and the bottom side screw devices so that an upper surfaceof the bottom work roll reaches a pass line of the rolled material; andsetting the eccentric angle of the fourth backing bearings by adjustingthe top side screw devices so that a ratio of a force received by therolled material from the top work roll to a force applied by the topscrew device to the third backing bearings is maximized.
 2. The rollposition setting method according to claim 1, including calculating theeccentric angle of the third backing bearings in a roll gap closecondition.
 3. The roll position setting method according to claim 2,including calculating the eccentric angle of the third backing bearingsin the roll gap close condition using a rolling load applied to therolled material and thickness of the rolled material.
 4. The rollposition setting method according to claim 2, including calculating theeccentric angle of the third backing bearings in the roll gap closecondition using a prescribed offset from the pass line.
 5. A rollposition setting method for setting rolls of a Sendzimir mill thatincludes top and bottom work rolls which roll a rolled material, aplurality of backing bearings having an eccentricity mechanism, a bottomscrew device which adjusts eccentric angle of first backing bearings, ofthe backing bearings, arranged in a middle part, and which press thebottom work roll from below, bottom side screw devices which adjusteccentric angle of second backing bearings, of the backing bearings, andwhich press the bottom work roll from below, located on an entry sideand a delivery side of the first backing bearings, a top screw devicewhich adjusts eccentric angle of third backing bearings, of the backingbearings, located in a middle part, and which press the top work rollfrom above, and top side screw devices which adjust eccentric angle offourth backing bearings, of the backing bearings, located on an entryside and a delivery side of the third backing bearings, which press thetop work roll from above, the method comprising: setting the eccentricangles of the first and second backing bearings by adjusting the bottomscrew device and the bottom side screw devices so that an upper surfaceof the bottom work roll reaches a pass line of the rolled material; andsetting the eccentric angle of the fourth backing bearings by adjustingthe top side screw devices so that a cost function, which has theeccentric angle of the third backing bearings and the eccentric angle ofthe fourth backing bearings as variables, is minimized.
 6. The rollposition setting method according to claim 5, wherein the cost functionincludes, in part, the eccentric angle of the third backing bearings ina roll gap close condition.
 7. The roll position setting methodaccording to claim 6, including calculating the eccentric angle of thethird backing bearings in the roll gap close condition using a rollingload applied to the rolled material and thickness of the rolledmaterial.
 8. The roll position setting method according to claim 6,including calculating the eccentric angle of the third backing bearingsin the roll gap close condition using a prescribed offset from the passline.